I have a cycled 45 Gallon tank with 8 tigers and 6 danios. I like the looks of the Opaline Gourami. I would like to get two. I talked to the fish store and they can not help me on making sure I get a male and a female. How do I tell the differance? What are Opaline Gourami like? I also like Yo YO loaches, How many do I need ?